Conventionally, small laboratory animals such as mice, rats, guinea pigs, hamsters, or the like used in various medical experiments and verifications are bred in a laboratory (laboratory animal breeding room) which is well equipped such that sufficient management can be carried out against bacterial infection of the laboratory animals or against leakage of bacteria from the laboratory animals.
In a conventional laboratory animal breeding room, these laboratory animals are bred using a laboratory animal breeding device such that the laboratory animals are protected against microbes such as bacteria or such that leakage of microbes such as bacteria from the laboratory animal breeding room to the outside is prevented. Exemplary conventional laboratory animal breeding devices include device disclosed in Japanese Utility Model Registration No. 2506467 (Patent Document 1).
A laboratory animal breeding device disclosed in Patent Document 1 is formed of racks 22 disposed in a laboratory animal breeding room 21 and a plurality of breeding cages 28 mounted on the racks 22, as illustrated in FIGS. 12 to 14.
The rack 22 is provided with a rack body formed by arranging at predetermined intervals in a vertical direction (perpendicular direction) a plurality of shelf boards which extend in a horizontal direction (lateral direction) and supporting the shelf boards by a post. An air exhaust box 36 having an air exhaust chamber 23 formed therein is attached to a rear surface of the rack body so as to be in intimate contact with the rack body. An air supply box 38 having an air supply chamber 37 formed therein is attached to each side surface of the rack body so as to be in intimate contact with the rack body.
Spaces between the respective shelf boards of the rack 22 are cage receiving portions 35 in which a plurality of breeding cages 28 are placed. The plurality of the breeding cages 28 are arranged at substantially predetermined intervals in a lateral direction in each of the cage receiving portions 35. Laboratory animals are bred in the breeding cages 28. A plate which blocks a rear side of the cage receiving portions 35 is a casing plate of the air exhaust box 36 attached to the rear side of the rack body. Exhaust openings 25 are formed in a rear plate of the rack 22 which is formed of the casing plate substantially correspondingly to the locations of the breeding cages 28 placed in the cage receiving portions 35. The cage receiving portions 35 communicate with the air exhaust chamber 23 in the air exhaust box 36 through the respective exhaust openings 25.
Each shelf board is constructed of two partition walls vertically spaced at a predetermined interval and end plates for blocking the whole periphery between the partition walls. An air supply duct 26 is formed inside each shelf board. The air supply duct 26 in each shelf board communicates with the air supply chambers 37 in the air supply boxes 38 placed at both side ends of the rack body. Air outlets 27 the number of which corresponds to that of the breeding cages 28 placed in the cage receiving portions 35 are formed in a bottom surface (partition wall) of an upper shelf board over one cage receiving portion 35. Air supplied from the air supply chamber 37 to the air supply duct 26 blows out from the air outlets 27 toward the cage receiving portions 35. The air exhaust box 36 and the air supply boxes 38 are connected to an air conditioner and an air exhaust device (both not shown) placed outside the laboratory animal breeding room 21 through an air exhaust duct 24a and an air intake duct 24b, respectively.
As illustrated in FIG. 14, each of the breeding cages 28 is constructed of a cage body 39 having a size capable of accommodating a laboratory animal and an upper portion of which is open, and a cover 40 which sealably closes the open upper portion of the cage body 39. An air supply opening 29 is formed in an upper surface of the cover 40 while an air exhaust opening 31 is formed on a rear surface of the cover 40. Filters 30 and 32 are provided in the air supply opening 29 and the air exhaust opening 31, respectively. When each of the breeding cages 28 is placed in the cage receiving portion between the shelf boards, the air supply opening 29 in the upper surface of the cover of the breeding cage 28 is connected to the air outlet 27 formed in the lower surface of the upper shelf board, and clean air supplied to the air supply duct 26 from the air supply chamber 37 is directly supplied to the breeding cage 28 from the air outlet 27.
It is to be noted that ventilation inside the laboratory animal breeding room 21 is provided by a conditioned air outlet 33 for a room and a ventilation opening (air exhaust opening) 34 provided in a ceiling. To be more specific, ventilation inside the laboratory animal breeding room 21 and ventilation inside the respective breeding cages 28 are controlled by separate clean air supply systems. Patent Document 1: Japanese Utility Model Registration No. 2506467